Stimulus Control

Stimulus Control is involved in…

When to talk to strangers When to cross the street When to say hi to someone When to eat week-old food out of the

refrigerator When to say “reward” and

when to say “reinforcer”

When to hug vs. give hand shake to someone

Stimulus Control

Stimulus control is everything!

Most children with autism have difficulty emitting social and verbal behavior under appropriate stimulus conditions.

Response:

Scream

Reinforcer:

Break from work

SD:

Teacher Joe

SΔ:

Teacher Jenny No break

Response:

“Open door”

Reinforcer:

Door is opened

SD:

Teacher

SΔ:

Peer Door is not opened

Response:

pinch

Reinforcer:

“ouch!”

SD:

Mom in room

SΔ:

Dad in room No response

Response:

Hold out picture of

spoon

Reinforcer:

spoon

SD:

Person in room

SΔ:

No one in room No spoon

Stimulus Control

Stimulus Discrimination

Stimulus Generalization

Stimulus Control

Stimulus DiscriminationDefinition: Degree to which antecedent stimuli

set the occasion for particular responses• precise degree of stimulus control

• E.g., Man has beard and is Daddy; Man has beard and is Uncle Eddie

• Stimulus discrimination is taught by using discrimination training procedures such as differential reinforcement

Stimulus Control

Stimulus GeneralizationDefinition: When a response is reinforced in the

presence of one stimulus there is a general tendency to respond in the presence of new stimuli that have similar physical properties ore have been associated with the stimulus.• loose degree of stimulus control

• E.g., All men with beards are Daddy

• Cannot be taught –but can plan for it

Development of Stimulus Control

Stimulus discrimination training Requires one behavior Two antecedent stimulus conditions (the SD and the S)

Responses that occur in the presence of the SD are reinforced (thus, the response increases in the presence of the SD)

Responses that occur in the presence of the S are not reinforced (this, the response decreases in the presence of the S Can also result in a lesser amount or quality of

reinforcement

Development of Stimulus Control

Example: Reinforcing a child’s saying “red” when someone asks “What’s your favorite color?” and witholding reinforcement if they said “red” when asked “ What’s your name?”

Response:

“red”Reinforcer:

“Super! You said red!”

SD:

“What’s your favorite color?”

SΔ:

“What’s your name?”

No praise

Differential Responding

When a child’s behavior comes under the control of the SD, We say the SD has acquired stimulus control

over the child’s behaviorSo the verbal stimulus “What’s your favorite

color?” gains stimulus control over the response “red” – why?

And the child is discriminating or responding differentially

Stimulus Generalization

When a response is reinforced in the presence of one stimulus,That same type of behavior tends

to be evoked by stimuli that share similar physical properties with that controlling antecedent stimulus

Stimulus GeneralizationIf you teach “green” using this color circle …

Student’s most likely

to say “green”

Student’s less likely to say

“green” (discrimination)

Student’s less likely to say

“green” (discrimination)

Stimulus Generalization

So…when a response has been trained with a specific teacher, materials, or setting

It may occur with other, similar teachers, materials, or settings

The more similar the novel teacher, materials, and setting are to the training teacher, materials, and setting…The more likely stimulus generalization will

occur

Discrimination vs. Generalization

Essentially opposite processesAs one increases, the other decreases

DiscriminationResponding differently to 2 or more

stimuliTight degree of stimulus control

GeneralizationResponding similarly to 2 or more stimuliLoose degree of stimulus control

Stimulus Discrimination and Stimulus Generalization are a

Continuum

Stimulus

Discrimination

Stimulus

Generalization

Why Teach Discriminations?

Discrimination is a fundamental process that controls behavior.

Discrimination allows us to differentiate when reinforcement is available for specific responses.

Why Teach Discriminations?

Many essential tasks require discrimination skillsReading.Labeling Objects.Following directions.Following activity schedules.Greeting people.Self-care skills.

Basic Problem of Discrimination Training

Discrimination training teaches learners to perform a specific response in the presence of a specific stimulus and not to perform that response in the presence of other stimuli.

Discrimination Training

Many individuals with developmental disabilities have difficulty learning discriminations

Stimuli are compound (they consist of different elements)It may be difficult to control which element(s) of

the stimulus exert control over behaviorWe must be careful how we teach and what

stimuli we use!

Stimulus Compounding

All stimuli are compound.They consist of many different

elements.

It is difficult to control which element or elements of the stimulus exert control over behavior.We need to be careful how we teach

and what stimuli we use.

2 Types of Discriminations.

Simple Discriminations.Non-Conditional Discrimination.

Conditional Discriminations.Matching-to-sample.Arbitrary Discrimination.

Simple Discrimination

Stimulus is present or not present One picture on the table that’s a “cat” Say

touch “cat” and they do

Not very useful for children with autismThat kind of trial becomes stimulus

independent which is what you DON”T want to happen

Conditional Discrimination

A response to a given stimulus is followed by a reinforcer if and only if another stimulus is present

Said another way…a stimulus is discriminative for reinforcement or not, depending on (conditional on) the presence of another particular antecedent

Often taught via Match-to-Sample procedures• Many programs consist of Identity Matching (matching identical

stimuli):• Objects• Pictures• Letters• Shapes• Colors• Numbers

Match-to-Sample

SampleLearner 1st responds to sample (conditional stimulus)

Then responds to one of the comparison stimuli

SD/S+ SΔ/S- SΔ/S-

Match-to-Sample

SD/S+

Sample (Conditional Stimulus)

SD/S+

Sample (Conditional Stimulus)

Establishing New Forms of Conditional Stimulus Control

Identity matching (single mode) Visual: visualAuditory: auditory

Arbitrary matching (multimodal)Visual: auditoryAuditory: visualAuditory: tactile

Arbitrary Matching

Stimuli are not physically identical Examples

Match non-identical visual stimuli• Object to pic, printed word to picture, object to printed

word

Match auditory stimulus to visual stimulus (“Receptive Identification”)

Others?

Receptive Picture ID

“flower” “baby”

SD/S+

Sample

SD/S+

Sample

Discrimination in the Laboratory.

Many laboratory discrimination procedures have focused on understanding exactly which stimuli or which aspects of stimuli control responding.

Several laboratory procedures have been developed that allow us to isolate these stimulus control factors. Matching-to-Sample. Equivalence Class Formation.

Concept Formation

Definition: Complex stimulus control that results in generalization within a class of stimuli and discrimination between classes of stimuli (Keller & Schoenfeld, 1950).

Two Procedures to Teach Concept Formation:

Simultaneous Discrimination: Definition: The concurrent presentation of multiple stimuli

Successive Discrimination Definition: The successive presentation of stimuli

In applied settings, simultaneous discrimination training should be used –why? The individual has access to all relevant stimulus cues at one

time An on the spot comparison of choices is permitted Produces better generalization (Schroeder & Baer, 1972)

Classroom Teaching Procedures.

Classroom teaching is more complex than the laboratory. Suggestions for improving discrimination training

• Evaluate stimuli carefully to promote control of relevant antecedent cues

• Rotate stimulus placement randomly• Change auditory stimuli frequently• Be sure that the S+/S- functions of stimuli change randomly• Teach with a variety of stimuli to promote discrimination

between categories (and generalization within categories)

• Never, never teach in isolation!!

Classroom Teaching Procedures.

• NEVER, NEVER, NEVER teach in isolation!!

Stimulus Class

Stimulus Class: set of stimuli that have a common effect on behavior (evoke the same response class)

These would probably be in the same stimulus class for most people

Concept Formation

Complex stimulus control that results in:Generalization within a class of stimuli

andDiscrimination between classes of

stimuli

Stimulus Equivalence

Emergence of accurate responding to untrained and nonreinforced stimulus-stimulus relationsFollowing the reinforcement of responses to

some stimulus-stimulus relations 3 aspects

ReflexivitySymmetryTransitivity

DOG “dog”

A

B C

Reflexivity In the absence of training, person selects

an identical stimulus (AKA Generalized identity matching)

Logic is…A = A For example

Without specific training, the person matches

Symmetry

After being taught to match A to B, person can match B to A (without training)

Logic is…If A = B, then B = A For example

After being taught to match to

Person can match to

DOG

DOG

Transitivity

Critical test for stimulus equivalence – if you get transitivity, the stimuli are members of an equivalence class

After being taught to match A to B and B to C, person can match A to C (without training)

Logic is…If A = B and B = C, then A = C For example…

After being taught to match• to AND• to “dog”

Person can match to “dog”

DOG

DOG

Factors Affecting the Development of Stimulus Control

Reinforcement Differential reinforcement with rich schedules of

reinforcement

Preattending Skills Looking at instructor or materials, sitting up tall, no

stereotypy

Factors Affecting the Development of Stimulus Control

Stimulus Presentation Specificity of directions

• Should relate to response definition Opportunity to response

• Frequent, active opportunities to respond (active student learning) correctly leads to higher rates of academic achievement

Pacing of response opportunities• Higher pace often leads to superior performance and less

off-task behavior

Factors Affecting the Development of Stimulus Control

Salience of the stimuli Influences attention and ultimately the development

of stimulus control Dependent on the capabilities of an individual, the

past history of reinforcement, and the situation Multiple intelligences: some respond to instructional

stimuli in the visual modality more than the oral. This research has generated mixed results but it is

important to rule out sensory deficits and assess modality strength

Factors Affecting the Development of Stimulus Control

Masking and overshadowing Masking –even though one stimulus has control over

behavior, another stimulus blocks that control from being expressed

• E.g., Student knows answer but won’t answer in front of peers

Overshadowing –the presence of one stimulus condition interferes with the acquisition of control by another stimulus

• E.g., hallway may be more interesting that teacher’s presentation in the front of the classroom

Ways to overcome include to make changes to physical environment, make instructional stimuli as intense and centrally located as possible, reinforce behavior in the presence of the instructionally relevant stimuli